This invention relates to an improvement in optical video disks or digital audio disks.
An optical video disk is fabricated according to the following method: As shown in FIG. 1, signal pits 1a are formed in one side of a layer 1 of synthetic resin such as acrylic resin, and a reflecting film 2 of aluminum or the like is formed on the side of the layer 1 thus treated. A protective film 3 is formed on the reflecting film 2, to form one disk. Another disk is prepared according to the same method. Then, the protective films 3 and 3' are bonded to each other with an adhesive. In FIG. 1, like parts are designated by like reference numerals, but with primes added.
Heretofore, a solvent type adhesive has been employed to bond the protective films to one another. Therefore, the solvent type adhesive must be such as will not affect the synthetic resin and the reflecting surfaces. Thus, the selection of a suitable adhesive is considerably difficult. Furthermore, as the adhesive is liable to flow to the surfaces of the synthetic resin layers, the resultant product is often low in practical worth. On the other hand, as the adhesive is dried after being applied to bond the two disks, dust may stick to the adhesive during the drying operation, thus spoiling the product; that is, with such a product, noise is produced during reproduction.